Production of motor fuels

ABSTRACT

COMPOSITE MOTOR FUELS OR GASOLINE, SUITABLE FOR USE AS A LEAD-FREE OR LOW-LEAD-CONTENT FUEL, ARE PROVIDED BY VARIOUS COMBINATIONS OF STEPS COMPRISING, IN DIFFERENT EMBODIMENTS, VARIOUS NOVEL COMBINATIONS OF STEPS COMPRISING CATALYTIC CRACKING, CATALYTIC REFORMING, AND SOLVENT EXTRACTION. IN SOME EMBODIMENTS, THE COMBINATION(S) INCLUDE ONE OR MORE ADDITIONAL STEPS SUCH AS HYDROCRACKING, ALKYLATION, AND DISPROPORTIONATION.

United States Patent 3,758,401 PRODUCTION OF MOTOR FUELS Ronald E. Bridgeford, Greenville, S.C., and Vernon A.

Cawi, Bartlesville, Okla., assignors to Phillips Petroleum Company Filed May 21, 1971, Ser. No. 145,847 Int. Cl. Cg 37/04, 37/00 US. Cl. 208-78 25 Claims ABSTRACT OF THE DISCLOSURE Composite motor fuels or gasoline, suitable for use as a lead-free or low-lead-content fuel, are provided by various combinations of steps comprising, in different embodiments, various novel combinations of steps comprising catalytic cracking, catalytic reforming, and solvent extraction. In some embodiments, the combination(s) include one or more additional steps such as hydrocracking, alkylation, and disproportionation.

This invention relates to the production of motor fuel or gasolines which are suitable for use as lead-free or low lead content fuels.

In recent years the problem of air pollution has been receiving increasing attention. Significant proportions of the population and governmental authorities at the various levels of government, federal, state, and local, are proposing and/or taking steps directed to reducing or eliminating various sources of pollutants in the atmosphere.

According to some groups, the exhaust gases emitted by the ordinary internal combustion engine contain pollutants which are responsible for a significant amount of air pollution; particularly in large population centers where the concentration of automobiles is large. It has been contended that the widely used antiknock agent, tetraethylled (TEL), is responsible for a substantial proportion of air pollution in such areas. According to other groups, antiknock agents such as said TEL are not responsible for a significant amount of air pollution.

Regardless of the merits of said opposing contentions, governmental authorities in some areas are taking steps which could require that TEL in motor fuels be eliminated, or at least reduced in amount. Pressure has been exerted on the automobile industry to design engines which will operate on lead-free or low lead content fuels. Similarly, pressure has been exerted on the petroleum industry to develop and supply lead-free or low lead content fuels for use in such engines. The present invention provides a solution for the problem facing the petroleum industry. The present invention provides various combinations of processing steps which cooperate to produce a gasoline or motor fuel which is suitable for use as a lead-free fuel or a low lead content fuel.

Thus, according to one embodiment of the invention, there is provided a process for producing a composite gasoline product of increased octane number, suitable for use as a lead-free motor fuel, comprising, in combination, the steps of: (a) cracking a feedstock comprising a low ice octane number light straight run gasoline in a first cracking zone and recovering from said cracking zone a cracked gasoline product of increased octane number; (b) catalytically cracking a feedstock comprising a gas oil in a second cracking zone and recovering from said second cracking zone a product stream comprising a light cracked gasoline and another product stream comprising a heavy cracked gasoline; (c) catalytically reforming a feedstock comprising said heavy cracked gasoline from step (b) in a first reforming zone and recovering a reformate from said first reforming zone; (d) solvent extracting said reformate from step (c) in a solvent extraction zone and recovering therefrom an extract stream comprising aromatic hydrocarbons, and a ratfinate stream comprising nonaromatic hydrocarbons; (e) passing at least a portion of said raffinate stream from step (d) to said step (a) as a portion of said feedstock therein; and (f) combining gasoline product from said step (a) and light cracked gasoline product from said step (b) to produce said composite gasoline product.

In another embodiment of the invention, there is provided, in further combination, the step of: (g) passing at least a portion of said light cracked gasoline recovered in said step (b) to said step (a) as a portion of said feedstock therein; and in said step (f) said composite gasoline product comprises said gasoline product from step (a).

In another embodiment of the invention, there is provided a process wherein: in said step (b) there is also recovered a stream of cracked cycle oils, and said process for producing a composite gasoline comprises, in further combination, the steps of: (h) hydrocracking said stream of cracked cycle oils in the presence of hydrogen in a hydrocracking zone and recovering from said zone a product stream comprising a light hydrocracked gasoline and another product stream comprising a heavy hydrocracked gasoline; (i) passing at least a portion of said light hydrocracked gasoline from said step (h) to said step (a) as a portion of said feedstock therein; and (j) passing said heavy hydrocracked gasoline from said step (h) to said step (c) as a portion of said feedstock therein.

In all the above embodiments of the invention, there can also be recovered in the various steps of the combination(s) a product stream comprising C olefins, a product stream comprising C olefins, and/or a product stream comprising C olefins. Thus, in various other embodiments of the invention, at least a portion of each of said olefin streams can be used to alkylate isobutane to produce alkylate product streams. For example, said C olefin stream(s) can be used to alkylate isobutane in the presence of a catalyst comprising aluminum chloride to produce a diisopropyl-rich alkylate; and said C olefin stream(s) and said C olefin stream(s) can be used to alkylate isobutane in the presence of a catalyst comprising hydrogen fluoride. If desired, in still other embodiments of the invention, at least a portion of said C olefins, instead of being used to alkylate isobutane, can be charged to a triolefin process. In said triolefin process, said C olefins undergo olefin disproportionation into C 3 and C olefins. At least a portion of the thus-obtained C and C olefins can then be used to alkylate isobutane as described above.

In the various embodiments of the invention described above, at least a portion of the aromatic concentrate stream produced in the solvent extraction step (d) can, if desired, be combined in step (f) with the gasoline product stream(s) to produce the composite gasoline product of the invention.

The drawing is a diagrammatic flow sheet illustrating various embodiments of the invention. It will be understood that many valves, pumps, control instruments, and other conventional equipment, not necessary for explaining the invention, have been omitted for the sake of brevity. It will also be understood that some streams produced in various processing steps of the invention, which are not necessary for explaining the invention, have also been omitted for the sake of brevity. The individual processing steps, per se, are known in the art and individually form no part of the present invention. As set forth in the appended claims, the invention resides in the various combinations of said steps.

The drawing and the invention will be further described with reference to the following calculated examples.

EXAMPLE I In this example of the prior art, 1,232 barrels per day of a light straight run gasoline boiling within the range of from about 80 to about 200 F., and obtained from a Mid-Continent crude oil in a crude oil distillation unit (not shown), is charged via conduit to a naphtha cracking zone 12. Said naphtha cracking zone 12 comprises a conventional naphtha cracking unit and associated equipment and can be operated under any suitable conditions known to the art. For the purposes of this run, said light straight run gasoline is cracked in a furnace in the presence of steam, at a steam/hydrocarbon weight ratio of about 1:2, at a temperature of about 1600" F., and a pressure of about 10 p.s.i.g. From this operation there is recovered 1,063 barrels per day of a product stream comprising ethylene which is removed via conduit 14, 478 barrels per day of a product stream comprising propylene which is removed via conduit 16, and 305 barrels per day of a gasoline product having a nominal end point of about 400 F. Said gasoline product is removed via conduit 18 and can be passed via conduits 20, 22, and 24 into gasoline storage 26.

In another prior art operation, 24,891 barrels per day of gas oil boiling within the range of about 600 to about 800 F., and obtained from said crude oil, are charged via conduit 36 to catalytic cracking zone 38. Said catalytic cracking zone 38 comprises a conventional fluid catalytic cracking zone and associated equipment and can be operated under any suitable conditions known to the art. For the purposes of this example, said gas oil is contacted with a conventional fluid catalytic cracking catalyst comprising silica-alumina at a temperature of about 920 F., and a pressure of about 25 p.s.i.a. From this operation there is recovered 1,615 barrels per day of a product stream comprising propylene which is removed via conduit 40, 2,060 barrels per day of a product stream comprising butylenes which is removed via conduit 42, 5,070 barrels per day of a light catalytic gasoline product stream boiling within the range of about 70 to about 225 F. which is removed via conduit 44, 7,600 barrels per day of a heavy catalytic gasoline product stream boiling within the range of about 225 to about 400 P. which is removed via conduit 46, and 7,180 barrels per day of a product stream comprising cycle oils boiling within the range of about 400 to about 700 F. which is removed via conduit 48. Said light catalytic gasoline in conduit 44 and said heavy catalytic gasoline in conduit 46 can be combined in conduit 50, and passed via conduits 22 and 24 into gasoline storage 26.

The ethylene product stream, the propylene product stream, and the butylene product stream produced in the above operations can be used to alkylate isobutane. For example, the ethylene stream in conduit 14 can be passed into alkylation zone 52 wherein it is used to alkylate isobutane in the presence of a catalyst comprising aluminum chloride, e.g., aluminum chloride-hydrocarbon complex catalyst, in known mannner. Said isobutane can be a prodnet of the above-described operations and introduced via conduit 53 and/or can include isobutane from an outside source introduced via conduit 54. Said alkylation zone 52 comprises a conventional alkylation unit and associated equipment employed for the purpose of alkylating isobutane with ethylene in the presence of aluminum chloride-containing catalysts and can be operated under any suitable conditions known to the art. For the purposes of this example, typical operating conditions include an isobutane to olefin mol ratio of 8 to 1, a temperature of about 100 F., a pressure sufficient to maintain liquid phase, and a hydrocarbon to catalyst volume ratio of about 1 to 1. An alkylate product stream in the amount of 1,679 barrels per day is withdrawn from zone 52 via conduit 56 and can be passed to composite gasoline storage 26.

The propylenes in conduit 40 from catalytic cracking zone 38 can be combined in conduit 16 with the propylenes from naphtha cracking zone 12, passed via conduit 57, and introduced via conduit 58 into alkylation zone 59. The butylenes in conduit 42 from said catalytic cracking zone 38 can also be passed into said conduit 58 for introduction into said alkylation zone 59. Said alkylation zone 59 comprises a conventional HF alkylation unit wherein the olefin feed stream is used to alkylate isobutane in known manner using any suitable conditions known in the art. For the purposes of this example, typical operating conditions in alkylation zone 59 would include an isobutane to olefin ratio of about 13 to l, a temperature of about F., a pressure sutficient to maintain liquid phase, and a catalyst to hydrocarbon volume ratio of about 4 to 1. An alkylate product stream in the amount of 7,329 barrels per day is withdrawn via conduit 61 and can be passed via conduits 22 and 24 into gasoline storage 26.

If desired, the combined propylene stream in conduit 16 can be passed via conduit 62 into triolefins process zone 63. Said triolefin process comprises a known process wherein propylene undergoes olefin disproportionation into ethylene and butylene. Said triolefin process can be operated in any manner and employing any suitable conditions known to the art, e.g., the conditions given in Pat. No. 3,365,513. For the purposes of this example, typical operating conditions in said triolefin process would include 300 p.s.i.g., 750 F., and a weight hourly space velocity of 100. A product stream comprising ethylene in the amount of 892 barrels per day is withdrawn from triolefin process zone 63 via conduit 64, at least a portion thereof combined with at least a portion of the ethylenes in conduit 14, and passed into said alkylation zone 52. When using all of said ethylene in this operation, the amount of alkylate produced and withdrawn via conduit 56 is 1,409 barrels per day. A product stream comprising butylenes in the amount of 1,091 barrels per day is withdrawn from triolefin process zone 63 via conduit 66, and at least a portion thereof can be passed via conduits 42 and 58, together with at least a portion of the butylenes in conduit 42 from catalytic cracking zone 38 into alkylation zone 59. When using all of said butylenes in this operation, the amount of butylenes alkylate produced in alkylation zone 59 is 1,964 barrels per day which is with drawn via conduit 61, and passed via conduits 22 and 24 into gasoline storage zone 26.

The results of the above-described operations are summarized in Table I under the heading of Example I.

EXAMPLE n In one embodiment of the invention, the operations described above in Example I for naphtha cracking zone 12, and catalytic cracking Zone 38, are carried out. In combination therewith, the 7,600 barrels per day of heavy cracked gasoline withdrawn from catalytic cracking zone 38 via conduit 46 is passed via conduits 67 and 68 into catalytic reforming zone 69. Said catalytic reforming zone 69 comprises a conventional reforming unit (Platforming unit) and associated equipment and can be operated under any suitable conditions known to the art. For the purposes of this example, typical operating conditions would include contacting said feedstock with a catalyst comprising platinum on alumina at a temperature of about 950 F. and a pressure of about 300 p.s.i.g. In this operation, there is produced 6,014 barrels per day of a cracked reformate which is withdrawn from said reforming zone 69 via conduit 71 and at least a portion thereof passed via conduit 72 into solvent extraction zone 73. Said solvent extraction zone 73 comprises a conventional solvent extraction unit and associated equipment. In said solvent extraction zone the feedstock is contacted in known manner with a suitable selective solvent (sulfolane) which selectively extracts from said feedstock the major portion of the aromatics contained therein. Any suitable selective solvent, e.g., liquid S0 phenol, diethylene glycol, etc., can be used in said solvent extraction zone. Typical operating conditions in said zone 73 would include a temperature of about 200 F., a pressure of about 50 p.s.i.g., and a solvent to hydrocarbon volume ratio of about 3 to 1. An extract stream comprising an aromatics concentrate stream in the amount of 2,823 barrels per day is withdrawn from zone 73 via conduit 74. A rafiinate stream comprising nonaromatic hydrocarbons from the feedstock is withdrawn from solvent extraction zone 73 via conduit 76 and at least a portion thereof combined with the light straight run gasoline in conduit as a part of the feedstock to naphtha cracking zone 12, previously described.

The use of all of said rafiinate as additional feedstock in said naphtha cracking zone 12 results in the production of an additional 2,754 barrels per day of ethylene, an additional 1,239 barrels per day of propylene, and an additional 791 barrels per day of gasoline. Said additional gasoline can be passed via conduits 18, 20, 22, and 24 into composite gasoline storage 26. Said additional ethylene can be passed via conduit 14, together with the ethylene produced in Example I, into alkylation zone 52, and therein used to alkylate isobutane as described in Example I. This additional ethylene results in increasing the alkylate production from alkylation zone 52 to 4,350 barrels per day. Said additional propylenes from naphtha cracking zone 12 are withdrawn via conduit 16 with the propylene produced as described in Example I above, and can be passed via conduits 57 and 58 into alkylation zone 59. Said additional propylenes result in increasing the production of alkylate product from zone 59 to 2,143 barrels per day.

If desired, said additional 1,239 barrels per day of propylenes, instead of being passed into HF alkylation zone 59, can be passed via conduits 16 and 62 into triolefin process zone 63, as described above in Example I. When said additional propylenes undergo disproportionation in triolefin process zone 63, as described above in Example I, there is produced an additional 527 barrels per day of ethylene. Said additional ethylene, when passed via conduits 64 and 14 into alkylation zone 52, results in the production of an additional 835 barrels per day of alkylate which can be removed via conduit 56 and passed to gasoline storage 26. Said disproportionation of said additional propylenes also results in the production of 643 barrels per day of butylenes which, when removed from triolefin process zone 63 via conduit 66 and passed via conduits 42 and 58 into alkylation zone 59, results in the production of 1,158 barrels per day of butylenes alkylate. Said butylenes alkylate is withdrawn via conduit 61 and can be passed via conduits 22 and 24 into gasoline storage 26.

The results of the above-described operation are summarized in Table I under the heading of Example II.

EXAMPLE III In another embodiment of the invention, the operations described above in Example II for naphtha cracking zone 12, catalytic cracking zone 38, catalytic reforming zone 69, and solvent extraction zone 73 are carried out. In combination therewith, at least a portion of the 5,070 barrels per day of light cracked gasoline removed from catalytic cracking zone 38 via conduit 44 is passed via conduits 50 and 77 into conduit 76, and then combined with the light straight run gasoline in conduit 10, along with the raffinate in conduit 76, as feedstock to naphtha cracking zone 12. From all of said additional light cracked gasoline feedstock there is produced in naphtha cracker 12 an additional 4,376 barrels per day of ethylene product which can be removed via conduit 14, an additional 1,969 barrels per day of propylene product which can be removed via conduit 16, and an additional 1,257 barrels per day of gasoline which can be removed via conduit 18. Said additional gasoline product can be passed with that previously produced in said naphtha cracking unit via conduits 20, 22, and 24 into gasoline storage 26. Said additional ethylene in conduit 14 can be passed to alkylation zone 52 and therein used to alkylate isobutane as previously described. Said additional ethylene results in the production of an additional6,920 barrels per day of diisopropyl-rich ethylene alkylate which is removed via conduit 56 and can be passed to gasoline storage 26. Said additional propylene in conduit 16 is passed, together with previouly produced propylene as described, into HF alkylation zone 59 wherein it is used to alkylate isobutane as previously described. Said additional propylene results in the production of an additional 3,415 barrels per day of propylene alkylate. Said additional propylene alkylate is withdrawn via conduit 61, along with previously produced alkylate product, and can be passed via conduits 22 and 24 into gasoline storage 26.

If desired, said additional propylene, instead of being passed into alkylation zone 59 as described, can be passed via conduits 16 and 62 into triolefin process zone 63 and therein disproportionated as previously described into a product stream comprising ethylene and another product stream comprising butylenes. The additional ethylene, 840 barrels per day, when passed via conduits 64 and 14 into alkylation zone 52, and therein used to alkylate isobutane as previously described, will result in the production of an additional 1,325 barrels per day of diisopropyl-rich ethylene alkylate. Said additional butylenes, when passed via conduits 66, 42, and 58 into alkylation zone 59, and therein used to alklate isobutane as previously described, will result in the production of an additional 1,840 barrels per day of butylenes alkylate.

The results of the above-described operations are summarized in Table I under the heading of Example III.

EXAMPLE IV In this example the operations described above in Example HI as carried out in naphtha cracking zone 12, catalytic cracking zone 38, catalytic reforming zone 69, and solvent extraction zone 73-, are carried out. In further combination therewith, 7,180 barrels per day of cycle oils, boiling within the range of about 400 to about 700 F., produced in catalytic cracking zone 38 are removed therefrom via conduit 48 and at least a portion thereof charged via conduit 78 into hydrocracking zone 79. Said hydrocracking zone comprises a conventional hydrocracking unit, e.g., UOP Isomax process, and associated equipment and can be operated under any suitable conditions known to the art. In such units the feedstock thereto is catalytically cracked in the presence of added hydrogen which can be introduced to the unit via conduit 81. For the purposes of this example, said cycle oils are contacted with a catalyst comprising nickel on silica-alumina at a temperature of about 800 F. and at 1600 p.s.i.g. The amount of hydrogen added is about 2,500 cubic feet per barrel of oil charged. From this operation, when charging all of said cycle oils, there is recovered 1,815 barrels per day of a light hydrocracked gasoline boiling within the range of from about 70 to about 160 F. There is also recovered 5,670 barrels per day of a heavy hydrocracked gasoline boiling within the range of about 160 to about 400 F. Said light hydrocracked gasoline is removed from hydrocracking zone 7'9 via conduit 82, at least a portion thereof passed via conduit 83 into conduit 76, and then into conduit 10 as a portion of the charge to naphtha cracking zone 12. Said heavy hydrocracked gasoline is withdrawn from hydrocracking zone 79 via conduit 84, at least a portion thereof passed into conduit 68, and then into catalytic reforming zone 69 as a portion of the charge stock thereto. The use of all of said heavy hydrocracked gasoline as additional charge to catalytic reforming zone 69 results in the production of an additional 4,486 barrels per day of cracked gasoline. Said additional cracked gasoline is withdrawn via conduit 71 and passed via conduit 72 into solvent extraction zone 73 wherein it is solvent extracted as previously described, resulting in the production of an additional 2,380 barrels per day of rafiinate. Said additional raflinate is withdrawn via conduit 76 and passed into conduit 10 as an additional portion of the feedstock to naphtha cracker 12.

Said additional feedstock of light hydrocracked gasoline in conduit 83 and said additional rafiinate results in the production from said naphtha cracker of an additional 3,621 barrels per day of ethylene, an additional 1,629 barrels per day of propylene, and an additional 1,040 barrels per day of gasoline. Said additional gasoline is withdrawn via conduit 18 and can be passed via conduits 20, 22 and 24 into gasoline storage 26. Said additionalethylene when used to alkylate isobutane in alkylation zone 52, as previously described, results in the production of an additional 5,735 barrels per day of diisopropyl-rich ethylene alkylate. Said ethylene alkylate is withdrawn from zone 52 and can be passed via conduit 56 into gasoline storage 26. Said additional propylene when used to alkylate isobutane in alkylation zone 59, as previously de scribed, results in the production of an additional 2,825 barrels per day of propylene alkylate. Said additional propylene alkylate is withdrawn via conduit 61 and can be passed via conduits 22 and 24 into gasoline storage 26.

If desired, said additional propylene stream, instead of being used to alkylate isobutane in alkylation zone 59, can be passed into triolefin process zone 63 and therein disproportionated as previously described into ethylene and butylenes. The ethylene produced in triolefin process Zone 63, in the amount of 692 barrels per day, when passed to alkylation zone 52 and therein used to alkylate isobutane, as previously described, results in the production of 1,095 barrels per day of diisopropyl-rich ethylene alkylate. This ethylene alkylate can be withdrawn via conduit 56 and passed into composite gasoline storage 26. The butylenes produced in triolefin process zone 63, in the amount of 845 barrels per day, when passed via conduits 66, 42, and 58 into alkylation zone 59, and therein used to alkylate isobutane as previously described, results in the production of 1,520 barrels per day of butylen'e alkylate. Said butylene alkylate is withdrawn via conduit 61 and can be passed via conduits 22 and 24 into gasoline storage 26.

The results of the above-described operation are summarized in Table I under the heading of Example IV.

EXAMPLE V The operations described above in Example IV for naphtha cracking zone 12, catalytic cracking zone 38, catalytic reforming zone 69, hydrocracking zone 79, and solvent extraction zone 73 are carried out. In combination therewith, 18,536 barrels per day of a heavy straight run gasoline boiling within the range of about 200 to about 300 F., obtained from said crude oil, is charged via conduits 28 and 30 to catalytic reforming zone 32. There is also charged to said reforming zone 32, via conduit 29, 5,671 barrels per day of a naphtha, obtained from said crude oil, and boiling within the range of about 300 to about 400 F. Said catalytic reforming zone 32 comprises a conventional reforming unit, e.g., a Platforming process, and associated equipment and can be operated under any suitable conditions known to the art. For purposes of this example, the feedstock to said reforming unit is contacted with a catalyst comprising platinum on alumina at a temperature of about 950 F., and 300 p.s.i.g. From this operation there is recovered 18,150 barrels per day of reformed gasoline which is withdrawn via conduit 34. Said gasoline product can be passed via said conduit 24 into gasoline storage 26 or, in one preferred embodiment, can be passed via conduit 86 to solvent extraction zone 73. In said solvent extraction zone, said reformed gasoline is solvent extracted, as previously described, to yield an additional 9,630 barrels per day of raffinate and an additional 8,520 barrels per day of an aromatic concentrate stream. Said raffinate is withdrawn via conduit 76 and at least a portion thereof passed via conduit 10 into naphtha cracking zone 12 as an additional portion of the feedstock thereto. The use of all of said raftinate as additional feedstock results in the production from said naphtha cracker 12 of an additional 8,312 barrels per day of ethylene, an additional 3,740 barrels per day of propylene, and an additional 2,387 barrels per day of gasoline. S aid additional gasoline is withdrawn via conduit 18 and can be passed to gasoline storage 26 as previously described.

Said additional ethylene, when used to alkylate isobutane in alkylation zone 52 as previously described, results in the production of an additional 13,165 barrels per day of diisopropyl-rich ethylene alkylate which can be passed to gasoline storage 26 as previously described. Said additional propylene, when used to alkylate isobutane in alkylation zone 59 as previously described, results in the production of an additional 6,486 barrels per day of propylene alkylate. Said additional propylene alkylate can be passed to gasoline storage 26 as previously described.

Said additional propylene, instead of being passed to alkylaton zone 59, can be passed to triolefin process zone 63 and therein disproportionated into ethylene and butylenes, as previously described. The 1,590 barrels per day of ethylene produced in triolefin process zone 63, when used to alkylate isobutane in alkylation zone 52 as previously described, results in the production of an additional 2,514 barrels per day of diisopropyl-rich ethylene alkylate. The 1,940 barrels per day of butylenes produced in triolefin process zone 63, when used to alkylate isobutane in alkylation zone 59 as previously described, results in the production of 3,490 barrels per day of butylenes alkylate. Said ethylene alkylate and said butylenes alkylate can be passed to gasoline storage 26, as previously described.

The results of the above-described operation are summarized in Table I under the heading of Example V. In all the examples set forth in Table I, there is included in the gasolines 700 barrels per day of isopentanes recovered from the operation of the crude oil distillation unit, not shown.

TABLE I Without aromatics With aromatics With With TOP TOP 6 No. With plus No. With plus allrys alky. alky. alky. alky. alky.

Example 1:

C5 plus gasoline, B/D 13, 675 22, 683 22,435 RON clear 92. 8 92.9 94. 7 Reid vapor press 5. 7 5. 4 5. 5 Example II:

plus gasoline, B/D....- 6, 866 22,367 21,969 9, 689 25, 190 24, 792 RON, clear 95. 0 95. 1 98. 1 99. 3 96.8 99. 5 Reid vapor press-.- 9. 7 6. 8 7. 0 7. 7 6. 4 6. 5 Example III:

05 plus gasoline, BID.-- 3, 053 28, 889 28, 241 5, 876 31, 712 31, 064 RON, clear 9.5 6.5 100.1 1 3.1 97.3 100.5 Reid vapor press 5. 8 5. 9 6. 1 4. 4 5. 6 5. 8 Example IV:

0 plus gasoline, B/D- 4, 093 38,489 37, 631 9, 022 43,418 42,560 RON, clear 100. 0 6. 7 100.2 103. 8 97. 8 100.9 Reid vapor press... 4. 7 5. 9 6. 0 3. 8 5. 6 5. 7 Example V:

05 plus gasoline, B/D 6,480 60,527 59, 187 19,929 73, 976 72, 636 RON, clear 100.4 7. 3 100.7 104.9 98.9 101. 7 Reid vapor press 3. 5 5. 9 6. 1 3. 1 5. 3 5. 5

I No alkylation.

e Triolefin process, 02 olefin converted to C3 and C4 olefin C2 olefin, isobutane alkylation, A101 catalyst; C olefin, isobutane alkylation, HF

catalyst.

s Research octane number.

The above examples illustrate the real and effective cooperation obtained in the practice of the invention between the steps of the combinations of the invention. For example, comparing Example II with Example I, when the heavy cracked gasoline from catalytic cracking zone 38 is reformed in catalytic reforming zone 69, and the reformate gasoline is solvent extracted in solvent extraction zone 73 to produce a rafiinate which is used as additional charge stock in naphtha cracking zone 12, there is obtained an increase in octane number of the composite gasoline from 92.8 to 95.0. Comparing the figures in columns 2 and 3 shows that the octane number increases from 92.9 to 95.1 when using alkylation, and from 94.7 to 98.1 when using alkylation plus the triolefin process, with the production of substantially the same amount of gasoline. The use of the naphtha cracking zone 12 to upgrade the gasoline feedstocks charged thereto and concomitantly produce olefins which can be used to alkylate isobutane, as in the combinations of the invention, is particularly advantageous in areas where natural gas liquids are being processed and there is a good supply of isobutane.

The data in columns 4, 5, and 6 set forth the advantages of blending back the aromatic concentrate stream produced in solvent extraction step (d). For example, comparing the figures in column 2 for Example I with the figures in column 5 for Example II shows there is an increase in octane number from 92.9 to 96.8 and an increase of about 2,500 barrels in the amount of the composite gasoline. Comparing column 3 for Example I with column 6 for Example II shows there is an even greater increasee in the octane number.

Similar comparisons can be developed for the combinations illustrated by Examples HI, IV, and V. All the examples illustrate the advantages of using one or more other processing steps, e.g., catalytic cracking zone 38, catalytic reforming zone 69, hydrocracking zone 79, and solvent extraction zone 73 for preparing additional feedstock for the naphtha cracker unit 12. Analysis of the data in Table I shows that the use of the solvent extraction zone is particularly advantageous. The data shows it is advantageous to employ solvent extraction to separate relatively low value hydrocarbon stocks into a substantially nonaromatic raffinate and an aromatic concentrate extract. Said raffinate can then be upgraded to high octane number gasoline with further production of olefins which can be used to alkylate isobutane with the production of high octane number alkylates which can be used to further increase the production of the composite gasoline product.

If desired, in the above combinations illustrated in Examples II, III, and IV, and also in the prior art Example I, the reformate gasoline from catalytic reforming zone 32 can also be included in the composite gasoline.

Further details regarding the operation of naphtha cracking units such as employed in naphtha cracking zone 12 can be found, for example, in Hydrocarbon Processing, page 174, November 1967, Gulf Publishing Co., Houston, Tex. Further details regarding the operation of catalytic reforming units such as employed in reforming zones 32 and 69 can be found, for example, in Hydrocarbon Processing, page 189, September 1970, Gulf Publishing Co., Houston, Tex. Further details regarding the operation of catalytic cracking units such as employed in zone 38 can be found, for example, in said September 1970, Hydrocarbon Processing, page 175. Further details regarding the operation of hydrocracking units such as employed in hydrocracking zone 79 can be found, for example, in said September 1970, Hydrocarbon Processing, page 168. Further details regarding the operation of alkylation units such as employed in zones 52 and 59 can be found, for example, in said September 1970, Hydrocarbon Processing, pages 200 and 202, respectively. Further details regarding the operation of a triole-fin proces unit such as employed in zone 63 can be found in US. Pat. 3,365,513.

While certain embodiments of the invention have been described for illustrative purposes, the invention is not limited thereto. Various other modifications or embodiments of the invention will be apparent to those skilled in the art in view of this disclosure. Such modifications or embodiments are Within the spirit and scope of the disclosure.

We claim:

1. A process for producing a composite gasoline prodnot of increased octane number, suitable for use as a leadfree motor fuel, comprising, in combination, the steps of:

(a) cracking a feedstock comprising a low octane number light straight run gasoline in a first cracking zone and recovering from said cracking zone a cracked gasoline product of increased octane number;

(b) catalytically cracking a feedstock comprising a gas oil in a second cracking zone and recovering from said second cracking zone a product stream compris- 1 1 ing a light cracked gasoline and another product stream comprising a heavy cracked gasoline;

(c) catalytically reforming a feedstock comprising said heavy cracked gasoline from step (b) in a first reforming zone and recovering a reformate from said first reforming zone;

(d) solvent extracting said reformate from step (c) in a solvent extraction zone and recovering therefrom an extract stream comprising aromatic hydrocarbons, and a raffinate stream comprising nonarornatic hydrocarbons;

(e) passing at least a portion of said raffinate stream from step (d) to said step (a) as a portion of said feedstock therein; and

(f) combining gasoline product from said step (a) and light cracked gasoline product from said step (b) to produce said composite gasoline product.

2. A process according to claim 1 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (b) there is also recovered a product stream comprising C olefins, and another product stream comprising 0., olefins;

at least a portion of said C olefins product stream, at least a portion of said C olefins product stream, and at least a portion of said 0.; olefins product stream are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

3. A process according to claim 2 wherein:

said C olefins are used to alkylate isobutane in the presence of a catalyst comprising aluminum chloride to produce a diisopropyl-rich alkylate product; and

said C olefins and said C olefins are used to alkylate isobutane in the presence of a catalyst comprising hydrogen fluoride.

4. A process according to claim 2 wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline 5. A process according to claim 1 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (c) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

at least a portion of said C olefins are disproportionated to produce a product stream comprising C olefins and another product stream comprising C olefins;

at least a portion of said C olefins product stream, and at least a portion of said C olefins product stream, are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

6. A process according to claim 5 wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product streams in producing said composite gasoline.

7. A process according to claim 1 wherein said process comprises, in further combination, the step of:

in said step (f) said composite gasoline product comprises said gasoline product from step (a).

8. A process according to claim 7 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (c) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

at least a portion of said C olefin product stream, at least a portion of said 0;, olefins product stream, and at least a portion of said C olefins product stream are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

9. A process according to claim 8 wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product in producing said composite gasoline.

10. A process according to claim 7 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (0) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

at least a portion of said C olefins are disproportionated to product a product stream comprising C olefins and another product stream comprising C olefins;

at least a portion of said C olefins product stream, and at least a portion of said 0.; olefins product stream, are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasline product streams in said step (t) in producing said composite gasoline.

11. A process according to claim 10 wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product streams in producing said composite gasoline.

12. A process according to claim 7 wherein:

in said step (b) there is also recovered a stream of cracked cycle oils, and said process for producing a composite gasoline comprises, in further combination, the steps of:

(h) hydrocracking said stream of cracked cycle oils in the presence of hydrogen in a hydrocracking zone and recovering from said zone a product stream comprising a light hydrocracked gasoline and another product stream comprising a heavy hydrocracked gasoline;

(i) passing at least a portion of said light hydrocracked gasoline from said step (h) to said step (a) as a portion of said feedstock therein; and

(j) passing at least a portion of said heavy hydrocracked gasoline from said step (h) to said step (c) as a portion of said feedstock therein.

.13. A process according to claim I12 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (c) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

at least a portion of said C olefins product stream, at least a portion of said 0;, olefins product stream, and at least a portion of said C olefins product stream are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

14. A process according to claim 13 wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product in producing said composite gasoline.

15. A process according to claim 12 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step there is also recovered a product stream comprising C olefins, and another product stream comprising 0.; olefins;

at least a portion of said C olefins are disproportionated to produce a product stream comprising C olefins and another product stream comprising C olefins;

at least a portion of said C olefins product stream, and at least a portion of said C olefins product stream, are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

16. A process according to claim wherein at least a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product streams in producing said composite gasoline.

17. A process according to claim 12 wherein said process comprises, in further combination, the step of:

(k) catalytically reforming a feedstock comprising a heavy straight run gasoline and/or a naphtha in a second reforming zone and recovering from said zone a reformate gasoline product; and

passing at least a portion of said reformate gasoline product to said solvent extraction step (e).

:18. A process according to claim 17 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (0) there is also recovered a product stream comprising C olefins, and another product stream comprising 0., olefins;

at least a portion of said C olefins product stream, at least a portion of said C olefins product stream, and at least a portion of said C olefins product stream are each used to alkylate isobutane and produce alkylate product streams; and

said alkylateproduct streams are combined with said gasoline product streams in said step (g) in producing said composite gasoline.

19. A process according to claim 18 wherein at least .a portion of said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product in producing said composite gasoline.

20. A process according to claim 17 wherein:

in step (a) there is also recovered a product stream comprising C olefins, and another product stream comprising C olefins;

in step (c) there is also recovered a product stream comprising 0;, olefins, and another product stream comprising C olefins;

at least a portion of said C olefins are disproportionated to produce a product stream comprising C olefins and another product stream comprising C olefins;

at least a portion of said C olefins product stream, and at least a portion of said C olefins product stream 14 are each used to alkylate isobutane and produce alkylate product streams; and

said alkylate product streams are combined with said gasoline product streams in said step (f) in producing said composite gasoline.

21. A process according to claim 20 wherein said aromatic hydrocarbons produced in step (d) are also combined in step (f) with said gasoline product streams and said alkylate product streams in producing said composite gasoline.

22. A process for producing a composite gasoline product of increased octane number, suitable for use as a leadfree motor fuel, comprising, in combination, the steps of (a) thermally cracking a feedstock comprising a low octane number light straight run gasoline in a first cracking zone in the presence of steam and recovering from said cracking zone a cracked gasoline product of increased octane number;

7 (b) catalytically cracking a feedstock comprising a gas oil in a second cracking zone in the absence of added hydrogen and recovering from said second cracking zone a product stream comprising a light cracked gasoline and another product stream comprising a heavy cracked gasoline;

(c) catalytically reforming a feedstock comprising said heavy cracked gasoline from step (b) in a first reforming zone and recovering a reformate from said first reforming zone;

(d) solvent extracting said reformate from step (c) in a solvent extraction zone and recovering therefrom an extract stream comprising aromatic hydrocarbons, and a rafiinate stream comprising nonaromatic hydrocarbon;

(e) passing at least a portion of said raflinate stream from step (d) to said step (a) as a portion of said feedstock therein; and

(f) combining gasoline product from said step (a) and light cracked gasoline product from said step (b) to produce said composite gasoline product.

23. A process according to claim 22 wherein said process comprises, in further combination, the step of:

(g) passing at le ast a portion of said light cracked gasoline recovered in said step (b) to said step (a) as a portion of said feedstock therein; and

in said step (f) said composite gasoline product comprises said gasoline product from step (a).

24. A process according to claim 23 wherein:

in said step (b) there is also recovered a stream of cracked cycle oils, and said process for producing a composite gasoline comprises, in further combination, the steps of:

(h) hydrocracking said stream of cracked cycle oils in the presence of hydrogen in a hydrocracking zone and recovering from said zone a product stream comprising a light hydrocracked gasoline and another product stream comprising a heavy hydrocracked gasoline;

(i) passing at least a portion of said light hydrocracked gasoline from said step (h) to said step (a) as a portion of said feedstock therein; and

(j) passing at least a portion of said heavy hydrocracked gasoline from said step (h) to said step (c) as a portion of said feedstock therein.

25. A process according to claim 24 wherein said process comprises, in further combination, the step of:

(k) catalytically reforming a feedstock comprising a heavy straight run gasoline and/or a naphtha in a second reforming zone and recovering from said zone a reformate gasoline product; and

passing at least a portion of said reformate gasoline product to said solvent extraction step (e).

(References on following page) References Cited UNITED STATES PATENTS Evans 20865 N011 20865 Stine 20862 5 Stine 20862 Schuller 20860 Ross et a1 260683.1 Phillips 260683.45 Sweeney 20870 10 1 6 3,341,316 3/1969 Banks 260-683 2,740,751 4/ 1956 Haensel et a1. 20866 3,409,540 11/1968 Gould et a1 20879 DELBERT E. GANTZ, Primary Examiner G. E. S'CHMITKONS, Assistant Examiner US. Cl. X.R. 

